Home Building Envelopes and How They Influence Energy Efficiency

Published on: March 2, 2015
House made from money | AC Southeast®

The term “building envelope” refers to the parts of your home that form its exterior. The degree to which it insulates the inside of your home drives the overall energy efficiency. The condition of the attic and roof, insulation levels, windows and the amount of air leakage the envelope has all impact how much heating and cooling the interior will need.


Because it’s constantly exposed to the sun, the roof and attic influence the energy efficiency of your home a great deal. In the southeastern U.S., homes should have between 10 and 20 inches of insulation in the attic to prevent heat transfer. The most common kinds are fiberglass batt and loose cellulose. They’re both affordable products and easy to install.

Before adding insulation, it’s a good idea to evaluate the air leakage rates between the ceiling and the attic. Look for small cracks between chimneys, pipes and flues. If you have recessed lights that enter the attic, they may leak a good deal of conditioned air into the attic. Unless you’re experienced with wiring, it’s best to hire an electrician or contractor to seal them.

Exterior Walls

If you have uncomfortable rooms in your home, it may be due to a weakness in the building envelope in that area. Inadequate insulation in that wall could be the cause or a condition called thermal bridging, where the wall studs themselves are transferring heat energy into and out of your home. It’s caused by gaps between the studs and insulation. It also occurs with aluminum window frames that conduct heat constantly.

It’s possible to increase insulation in existing walls by blowing in loose cellulose or fiberglass insulation. You can also use shade screens on the windows, as long as the frame covers the aluminum frame. Sealing cracks around window frames and adding exterior door weatherstripping will stop air infiltration and prevent moisture damage, as well.

Learn more about tightening up your home’s building envelope from the pros at AirConditioningSoutheast.com, or contact us today to find an HVAC contractor near you!